import sys 
import math

input = sys.stdin.readline

def main():
    x1,y1,x2,y2 = map(float, input().rstrip().split())
    
    print(math.sqrt((x2-x1)**2 + (y2-y1)**2))
    
if __name__ == "__main__":
    main() import sys sys import math math input = sys.stdin.readline input sys.stdin.readline sys.stdin sys stdin readline def main():
    x1,y1,x2,y2 = map(float, input().rstrip().split())
    
    print(math.sqrt((x2-x1)**2 + (y2-y1)**2))
     main x1,y1,x2,y2 = map(float, input().rstrip().split()) x1 map(float, input().rstrip().split()) map float input().rstrip().split() ().rstrip().split ().rstrip() ().rstrip () input rstrip split y1 x2 y2 print(math.sqrt((x2-x1)**2 + (y2-y1)**2)) print math.sqrt((x2-x1)**2 + (y2-y1)**2) math.sqrt math sqrt (x2-x1)**2 + (y2-y1)**2 (x2-x1)**2 x2-x1 x2 x1 2 (y2-y1)**2 y2-y1 y2 y1 2 if __name__ == "__main__":
    main() __name__ == "__main__" __name__ "__main__" main() main input = sys.stdin.readline sys.stdin.readline input def main():
    x1,y1,x2,y2 = map(float, input().rstrip().split())
    
    print(math.sqrt((x2-x1)**2 + (y2-y1)**2))
     def main():
    x1,y1,x2,y2 = map(float, input().rstrip().split())
    
    print(math.sqrt((x2-x1)**2 + (y2-y1)**2))
     main
import sys 
import math

input = sys.stdin.readline

def main():
    x1,y1,x2,y2 = map(float, input().rstrip().split())
    
    print(math.sqrt((x2-x1)**2 + (y2-y1)**2))
    
if __name__ == "__main__":
    main()
